Geology of Brushy Creek quadrangle, Williamson County, Texas
The exposed bedrock of Brushy Creek Quadrangle, Williamson County, Texas, is of Albian to Coniacian Age. In ascending order, the outcropping formations are Comanche Peak, Edwards, "Kiamichi", Georgetown, Del Rio, Buds, Pepper, Eagle Ford, and Austin, Three lithologic subdivisions of the Edwards are recognised, and five members of the Georgetown limestone are differentiated on the basis of lithology and fossil content. The structural relief results from normal strike faults breaching a Gulfward dipping homocline. En echelon faults of the Balcones Fault Zone bisect the area from north to south. Limestone and dolomite are quarried near Round Rock, but the backbone of the economy is agriculture.